Your business takes off; you nail a round of VC funding; and suddenly your leadership needs blow wide open. There are so many moving parts — and not enough people at the top to keep them moving in the same direction.

The question isn’t whether you will find leadership talent. It’s out there. The question is:

Will you find transformational leaders?

The idea of the transformational leader first came to note in 1978, with James MacGregor Burns’ classic book, Leadership.

You might expect a man writing on leadership in 1970s America to be a titan of the Big Three auto companies, or perhaps a retired general. Burns was neither. He was an historian who chronicled American democracy and the lives of major presidents. He was a WWII veteran. And over the course of his war experience and scholarly research, Burns came to realize something was amiss in prevailing theories of leadership: they focused almost solely on the traits of leaders themselves.

Burns was more interested in understanding how leaders interact with the people they lead.

He knew that, sometimes, leaders and followers push each other toward higher levels of integrity and achievement. He wanted to know why that happened and how. He wanted to learn how to cultivate leaders who weren’t simply “effective” — but transformational.

Still, members of this sought-after 10% are not always easy to spot from a resume. So how do you identify transformational leaders in the recruitment process?

The key is to talk with the people your candidates have led.

People who have worked for transformational leaders will say certain, central things about them — often with little prompting.

Followers will report feeling inspired to do their best, most creative work for this individual. Transformational leaders have a natural enthusiasm and positive energy that’s infectious. People who have worked for them will talk easily and enthusiastically about their warmth, vibrancy, and energy. They’ll tell you how they and others felt motivated to go above and beyond when working under this person’s direction and leadership.

They will report that this individual understood their concerns and needs. Transformational leaders don’t simply look to “get work out of” their followers. They seek to understand the needs and motivations of the people they lead. They help problem-solve when things get rough. They check in. They follow up. The people who have worked for them should say so with no hesitation.

They will be able to tell you what this person stands for. Transformational leaders clearly articulate their values and act on them consistently. Former coworkers and staff will be able to tell you easily what this person expects, respects, and stands for. They’ll be able to offer concrete examples of behaviors that reflect this leader’s standards and integrity.

They will report that this person knows how to delegate. Transformational leaders know how to build trusted teams — which means they know how to delegate important aspects of work, sometimes in order to enhance their followers’ skills.

They will say they felt challenged. Transformational leaders don’t simply offer kudos and support: they push themselves and everyone around them to question their most basic assumptions and approach problems in new ways. People who have worked for your candidate shouldn’t simply report feeling inspired — they should report feeling like this person took them out of their comfort zones and helped them work and create in new ways.

High-growth companies that aspire to grow bigger without becoming better are ultimately companies that fail. Once you’ve started on that high-growth arc, you need transformational leaders on your executive team to catalyze talent, harness momentum, and help you build higher and better.

Look for these five defining features of transformational leaders when you speak with candidates and the people they’ve led.